[grumple]

When's the last time a major index lost 50% of its value? - 2008 crash due to deregulation

Does it happen every two years? - obviously not

Are stocks intended to be currency? - no

Stocks also are attached to real property - ownership in a revenue / profit generating company and their assets. Crypto is only a vehicle for speculation.

A currency should not experience regular crashes or explosions of value. Assets are generally more volatile by their very nature.